JP6866007B2 - A water-based two-component clear paint composition and a method for repairing and painting a painted body using the same. - Google Patents

Description

The present invention relates to an aqueous two-component clear coating composition useful for repair coating of metal products such as automobile outer panels, railroad vehicles, and industrial equipment, and a repair coating method for a coated body using the same.

In recent years, water-based paints have become widespread in place of organic solvent-based paints in order to reduce the release of VOCs (volatile organic compounds), which have an adverse effect on the environment and the human body, into the atmosphere.

For example, the outer panel portion of an automobile body or the like is generally coated with a multi-layer coating film composed of an undercoat coating film, an intermediate coating film, a topcoat coating film, and a clear coating film for the purpose of preventing corrosion and imparting an aesthetic appearance. Among these coating films, the undercoat coating film, the intermediate coating film, and the undercoat coating composition for forming the topcoat coating film, the intermediate coating composition, and the topcoat coating composition are being made water-based, but the topcoat is being used. At present, it is difficult to achieve the same performance and finished appearance as the solvent-based clear coating composition with respect to the clear coating composition, and its development is required.

Currently, solvent-based paints are being replaced by water-based paints for repair paints, but clear paints for automobile repair paints are widely used as two-component paints that can be cured under normal temperature drying or forced drying conditions. ..

For example, in Patent Document 1, the applicant applies to an aqueous dispersion of an acrylic resin having a specific hydroxyl value, acid value, weight average molecular weight and glass transition temperature obtained by radical polymerization of a secondary hydroxyl group-containing monomer in a specific amount. And proposed an aqueous two-component clear coating composition containing a specific polyisocyanate curing agent. According to this composition, it is possible to obtain a coating film having excellent dispersibility of the polyisocyanate curing agent and having excellent yellowing resistance even when overbaked. However, compared to organic solvent-based paints, water-based paints take longer to dry, which may cause sagging, resulting in insufficient drying and finish after coating, and improvements are still needed. There is. In particular, when an object to be coated with a rough substrate; for example, when spray-painted on an object to be coated or not polished or a colored base coating film, the roughness of the substrate is directly reflected on the topcoat surface to improve smoothness. In some cases, it was impaired and the finish such as glossiness and glossiness deteriorated.

International Publication WO2008 / 050756 Pamphlet

The present invention has been made in view of the above circumstances, and an object of the present invention is an aqueous two-component type in which the obtained coating film is extremely excellent in finish such as smoothness even on a highly coarse object to be coated. The present invention provides a clear coating composition and a method for forming a multi-layer coating film.

Under such circumstances, as a result of diligent research by the present inventors, a polyisocyanate compound containing two types of acrylic resins having different acid values in the main agent (I) and having an acid group in the curing agent (II), and a hydroxyl group. It has been found that the above-mentioned problems can be solved by using an aqueous two-component clear coating composition containing a glycol ether-based organic solvent that does not have the above.

The present invention provides an aqueous two-component clear coating composition shown in the following section and a repair coating method using the same:
Item 1. In an aqueous two-component clear coating composition containing an acrylic resin-containing main agent (I) and a curing agent (II), the main agent (I) contains an acrylic resin (A1) having an acid value of less than 40 mgKOH / g.
Acrylic resin (A2) having an acid value in the range of 100 to 300 mgKOH / g, and containing
A polyisocyanate compound (B) having an acid group in the curing agent (II) and
An aqueous two-component clear coating composition containing a glycol ether-based organic solvent (C) having no hydroxyl group.

Item 2. Item 2. The aqueous two-component clear coating composition according to Item 1, further comprising a tertiary amine (D) in the main agent (I).

Item 3. Item 3. The aqueous two-component clear coating composition according to Item 1 or Item 2, wherein the acrylic resin (A1) has a glass transition temperature of more than 40 ° C.

Item 4. The acrylic resin (A1) is a water-dispersible hydroxyl group-containing acrylic resin having a core-shell type structure, and the polymerizable unsaturated monomer component (X) constituting the core portion is an epoxy group-containing non-polymerizable resin. The polymerizable unsaturated monomer component (Y) containing the saturated monomer (a1), the hydroxyl group-containing polymerizable unsaturated monomer (a2) and the other polymerizable unsaturated monomer (a3) and constituting the shell portion is carboxyl group-containing polymerizable. Item 2. The aqueous two-component clear coating composition according to any one of Items 1 to 3, which comprises an unsaturated monomer (b1), a hydroxyl group-containing polymerizable unsaturated monomer (b2), and another polymerizable unsaturated monomer (b3). ..

Item 5. The acrylic resin (A2) contains (meth) acrylic acid and (meth) acrylate having an alkyl group having 1 to 2 carbon atoms as at least a part of the copolymerization component, and (meth) acrylic acid / carbon. Item 2. The aqueous two-component clear coating composition according to any one of Items 1 to 4, wherein the mass ratio of the (meth) acrylate of No. 1 to 2 is in the range of 10/90 to 70/30.

Item 6. Item 6. The item 1 to 5 in which the content of the acrylic resin (A2) is 0.01 to 20 parts by mass with respect to 100 parts by mass of the resin solid content of the acrylic resin (A1). Aqueous two-component clear paint composition.

Item 7. The aqueous two-component clear coating composition according to any one of Items 1 to 6, further comprising a polyether-modified siloxane (E) as a surface conditioner in the main agent (I) and / or the curing agent (II).

Item 8. A step of filling or coating a damaged part of a coated body with a base treatment agent to form a base treatment layer (1), a step of drying and polishing the formed base treatment layer (2), and a polished base treatment layer. Item 1 to item 1 to 7 on the step (3) of coating the colored base coat coating composition for repair to form a colored base coating film, and on the colored base coating film obtained in the step (3). A method for repairing and coating a coated body, which comprises a step (4) of coating and drying the aqueous two-component clear coating composition according to the above.

Item 9. Item 8. Repair of a coated body according to Item 8, wherein the colored base coat coating composition for repair is a water-based base coat coating composition containing a water-soluble resin and / or a water-dispersible resin, a coloring pigment and / or a bright pigment as a main component. Painting method.

When the aqueous two-component clear coating composition of the present invention is used, the obtained coating film is excellent in finishability such as smoothness even when the drying property is excellent and the roughness of the substrate is high. In addition, it is excellent in painting workability because it is less likely to cause sagging.

The present invention comprises a polyisocyanate compound containing two types of acrylic resins having different acid values in the main agent (I) and having an acid group in the curing agent (II), and a glycol ether-based organic solvent having no hydroxyl group. A water-based two-component clear coating composition comprising.

≪Main agent (I) ≫
≪Acrylic resin (A) ≫
In the present invention, as the acrylic resin (A), an acrylic resin (A1) having an acid value of less than 40 mgKOH / g per solid content and an acrylic resin (A2) having an acid value of 100 to 300 mgKOH / g per solid content are used in combination. It is characterized by doing.

<Acrylic resin (A1)>
In the present invention, the acrylic resin (A1) is not particularly limited as long as the acid value is less than 40 mgKOH / g, but it is particularly preferable to use a water-dispersible (emulsion) hydroxyl group-containing acrylic resin having a core-shell type structure. ..

In particular, the glass transition temperature (Tg) of the acrylic resin (A) is more than 40 ° C., preferably 40 to 90 ° C., from the viewpoint of hardening the obtained coating film and achieving both polishability and dryness of the clear coating film. Further, those in the range of 45 to 85 ° C. are suitable.

The method for producing the acrylic resin (A1) is not particularly limited, but it can be obtained, for example, by water-dispersing the acrylic resin obtained by polymerizing the polymerizable unsaturated monomer in the presence of an organic solvent. In particular, it is preferable to polymerize the polymerizable unsaturated monomer components having different compositions in multiple stages because the acrylic resin is excellent in water dispersibility and storage stability.

As a method of water-dispersing the acrylic resin, a part or all of anionic groups such as a carboxyl group contained in the acrylic resin are neutralized with a basic compound and dispersed in water, or a basic compound is contained. It is also possible to add and disperse the acrylic resin in the aqueous medium. It is preferable to distill off the organic solvent after the production of the acrylic resin as much as possible from the viewpoint of reducing VOC. The organic solvent may be distilled off under reduced pressure without cooling the acrylic resin while maintaining the reaction temperature (for example, 145 ° C.) at the time of resin synthesis, for example, until the solid content of the acrylic resin becomes 80% by mass or more. The temperature at the time of distillation under reduced pressure can be appropriately selected according to the type of solvent used for the synthetic resin. After distilling off the organic solvent under reduced pressure, for example, the temperature is set to about 90 ° C., a basic compound is added as a neutralizing agent to neutralize, and then a predetermined amount of deionized water is added dropwise at a temperature of about 80 ° C. with stirring. As a result, an aqueous dispersion of a hydroxyl group- and acid group-containing acrylic resin (A1), which is a particulate aqueous dispersion (also referred to as an emulsion), can be obtained.

As the polymerizable unsaturated monomer component (X) at at least one stage for producing the acrylic resin,
Epoxy group-containing polymerizable unsaturated monomer (a1),
It contains a hydroxyl group-containing polymerizable unsaturated monomer (a2) and another polymerizable unsaturated monomer (a3).

In the present invention, the epoxy group-containing polymerizable unsaturated monomer (a1) is reacted with the carboxyl group contained in the polymerizable unsaturated monomer component (Y) described later to form a copolymer with the polymerizable unsaturated monomer component (X). A monomer used to further improve the aqueous dispersion stability of an acrylic resin (A1) emulsion by grafting with a copolymer containing a polymerizable unsaturated monomer component (Y), for example, glycidyl (meth) acrylate. β-Methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allylglycidyl ether, etc. These can be used alone or in combination of two or more.

The hydroxyl group-containing polymerizable unsaturated monomer (a2) is used to introduce a hydroxyl group into the acrylic resin (A1) for reacting with the polyisocyanate curing agent described later, and to contribute to the water dispersibility of the acrylic resin (A1). (Meta) acrylics such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Monoesterate of acid and divalent alcohol having 2 to 8 carbon atoms; ε-caprolactone modified product of monoesteride of the (meth) acrylic acid and divalent alcohol having 2 to 8 carbon atoms; allyl alcohol and the like. These can be used alone or in combination of two or more.

The other polymerizable unsaturated monomer (a3) is a polymerizable unsaturated monomer other than the above-mentioned monomer (a2) and monomer (a3), and has, for example, the number of carbon atoms of methyl (meth) acrylate, ethyl (meth) acrylate and the like. A (meth) acrylate having an alkyl group of 1 to 2; an alkyl group having 3 to 4 carbon atoms such as n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, and tert-butyl acrylate. Acrylate having; n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate , "Isostearly acrylate" (trade name, manufactured by Osaka Organic Chemical Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl Alkyl or cycloalkyl (meth) acrylate having 6 or more carbon atoms such as (meth) acrylate; polymerizable unsaturated monomer having an isobornyl group such as isobornyl (meth) acrylate; polymerization having an adamantyl group such as adamantyl (meth) acrylate Sexual unsaturated monomer; polymerizable unsaturated monomer having a tricyclodecenyl group such as tricyclodecenyl (meth) acrylate; containing an aromatic ring such as benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene, etc. Polymerizable unsaturated monomer; vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriisopropoxysilane, γ- (meth) acryloyloxypropyl Trimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldiethoxysilane, γ- (meth) acryloyloxypropyltri Hydrolyzable silyls such as -n-propoxysilane, γ- (meth) acryloyloxypropyltriisopropoxysilane, vinyltriacetoxysilane, β- (meth) acryloyloxyethyltrimethoxysilane Polymerizable unsaturated monomer having a group; perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; polymerizable unsaturated monomer having a fluorinated alkyl group such as fluoroolefin Monomers; Vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2- Phosphoric acid group-containing polymerizable unsaturated monomer such as methacryloyloxypropyl acid phosphate; (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and other carboxyl group-containing polymerizable unsaturated monomer; (meth) acrylonitrile, Nitrogen-containing unsaturated monomers such as (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, and adducts of glycidyl (meth) acrylate and amines. A polymerizable unsaturated monomer having at least two polymerizable unsaturated groups in one molecule, such as allyl (meth) acrylate and 1,6-hexanediol di (meth) acrylate; 2-acrylamide-2-methylpropanesulfonic acid. , 2-Sulfoethyl (meth) acrylate, allyl sulfonic acid, 4-styrene sulfonic acid, etc .; polymerizable unsaturated monomers having sulfonic acid groups such as sodium salt and ammonium salt of these sulfonic acids; maleic anhydride, itaconic anhydride, etc. Examples thereof include polymerizable unsaturated monomers having an acid anhydride group such as citraconic anhydride, and these can be used alone or in combination of two or more.

In the present invention, as the other polymerizable unsaturated monomer (a3), a monomer (a4) having a homopolymer glass transition temperature of 0 ° C. or higher as a part of its components is more preferably a monomer (a4) having a glass transition temperature of 0 ° C. It is desirable that a monomer in the range of 40 to 120 ° C. is contained as a part of the copolymerization component thereof from the viewpoint of the polishability of the clear coating film.

Here, the glass transition temperature of the monomer in the present specification is the glass transition temperature of the homopolymer of each monomer in Polymer Handbook (4th Edition, edited by J. Brandup E. H. Immunogut). The glass transition temperature of a monomer not described in the document is when a homopolymer of the monomer is synthesized so as to have a weight average molecular weight of about 50,000 and the glass transition temperature is measured by differential scanning calorimetry. Use the value.

Specific examples of the monomer (a4) having a glass transition temperature of 0 ° C. or higher in the homopolymer include styrene, methyl methacrylate, and methacrylate having an alkyl group having 3 to 4 carbon atoms, for example, n-propyl methacrylate and i. -Propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, tert-butyl methacrylate, methacrylate having a branched alkyl group, for example, t-butyl methacrylate, methacrylate having a cyclic alkyl structure, for example, cyclohexyl methacrylate, isobornyl. Other examples include isostearyl acrylate, lauryl acrylate (also known as dodecyl acrylate), cetyl acrylate (also known as hexadecyl acrylate), and benzyl methacrylate.

Further, from the viewpoint of adhesion to the object to be coated and coating film hardness, it is particularly preferable to use at least one monomer selected from styrene, methyl methacrylate, and methacrylate having an alkyl group having 3 to 4 carbon atoms. preferable.

The monomer (a4) having a glass transition temperature of 0 ° C. or higher can be used alone or in combination.

When the monomer (a4) having a glass transition temperature of 0 ° C. or higher is used, the amount used is 50 to 100% by mass, preferably 70 to 95% by mass in the other polymerizable unsaturated monomer (a3). It is desirable that the content is within the above range from the viewpoint of the polishability of the clear coating film.

The acrylic resin for producing the aqueous dispersion of the acrylic resin (A1) in the present invention is a polymerizable unsaturated monomer component in addition to the polymerizable unsaturated monomer component (X) at at least one step of producing the acrylic resin. (Y) is a copolymerization component.

The polymerizable unsaturated monomer component (Y) is
Carboxyl group-containing polymerizable unsaturated monomer (b1),
It comprises a hydroxyl group-containing polymerizable unsaturated monomer (b2) and another polymerizable unsaturated monomer (b3).

As the carboxyl group-containing polymerizable unsaturated monomer (b1), an aqueous dispersion group is introduced into the acrylic resin (A1) and reacted with the epoxy group contained in the copolymer of the polymerizable unsaturated monomer component (X). It is also a monomer used to introduce a functional group, and specific examples thereof include (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, etc., which are used alone or in combination of two or more. can do.

The hydroxyl group-containing polymerizable unsaturated monomer (b2) is the same as the compounds listed in the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer (a2), and can be used alone or in combination of two or more of these. ..

The other polymerizable unsaturated monomer (b3) is a polymerizable unsaturated monomer other than the above-mentioned monomer (b1) and monomer (b2), and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, and n-propyl. (Meta) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) ) Acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Co., Ltd.) Alkyl or cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate; isobornyl. Polymerizable unsaturated monomer having an isobornyl group such as (meth) acrylate; Polymerizable unsaturated monomer having an adamantyl group such as adamantyl (meth) acrylate; Tricyclodecenyl group such as tricyclodecenyl (meth) acrylate Polymerizable unsaturated monomer having: benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene and other aromatic ring-containing polymerizable unsaturated monomer; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, Phosphoric acid group-containing polymerizable unsaturated monomers such as 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate; 2-acrylamide-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrene sulfonic acid and the like; polymerizable unsaturated monomer having a sulfonic acid group such as a sodium salt and an ammonium salt of these sulfonic acids; polymerizable having an acid anhydride group such as maleic anhydride, itaconic anhydride and citraconic anhydride. Unsaturated monomers, etc .; vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriisopropoxy Silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldiethoxysilane , Γ- (meth) acryloyloxypropyltri-n-propoxysilane, γ- (meth) acryloyloxypropyltriisopropoxysilane, vinyltriacetoxysilane, β- (meth) acryloyloxyethyltrimethoxysilane, etc. Polymerizable unsaturated monomer having a silyl group; perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; polymerizable non-polymerizable monomer having a fluorinated alkyl group such as fluoroolefin. Saturated monomer; vinyl compounds such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate; (meth) acrylonitrile, (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- Nitrogen-containing polymerizable unsaturated monomers such as (methacryloyloxy) ethyltrimethylammonium chloride, glycidyl (meth) acrylate and amines adduct; allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate and the like. Examples thereof include polymerizable unsaturated monomers having at least two polymerizable unsaturated groups in one molecule, and these can be used alone or in combination of two or more.

Further, the other polymerizable unsaturated monomer (b3) may contain the monomer (a4) having a glass transition temperature of 0 ° C. or higher as a part of its components, so that the clear coating film can be finished and polished. Suitable from the point of view of sex.

The monomer (a4) having a glass transition temperature of 0 ° C. or higher can be appropriately selected from the compounds listed in the description of the monomer (a4) and used, and among other polymerizable unsaturated monomers (b3). The content of the above is preferably 10% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more. Further, the total amount of the monomer (b3) may be the monomer (a4) having a glass transition temperature of 0 ° C. or higher.

In the acrylic resin (A1), the ratio of the monomers (a1) to (a3) used in the polymerizable unsaturated monomer component (X) can be appropriately adjusted as long as it is within the range of the present invention, and generally,
Monomer (a1) is 0.1 to 40% by mass, preferably 0.5 to 25% by mass,
Monomer (a2) is 10 to 54.9% by mass, preferably 15 to 44.5% by mass,
Monomer (a3) is 10 to 89.9% by mass, preferably 15 to 84.5% by mass,
Can be within the range of.

Further, the ratio of these monomers (b1) to (b3) used in the above-mentioned polymerizable unsaturated monomer component (Y) can be appropriately adjusted as long as it is within the range of the present invention, and generally,
Monomer (b1) is 5 to 60% by mass, preferably 10 to 50% by mass,
The monomer (b2) is 20 to 75% by mass, preferably 25 to 65% by mass,
The monomer (b3) is 20 to 75% by mass, preferably 25 to 65% by mass,
Can be within the range of.

Further, in these polymerizable unsaturated monomer components (X) and (Y), the carboxyl group contained in the polymerizable unsaturated monomer component (Y) with respect to 1 mol of the epoxy group contained in the polymerizable unsaturated monomer component (X). It is suitable that the amount is adjusted to be within the range of 3 to 30 mol, particularly 6 to 20 mol, from the viewpoint of the storage stability of the acrylic resin (A1) and the finish and polishability of the clear coating film. ing.

The ratio of the polymerizable unsaturated monomer components (X) and (Y) used is 60/40 to 95/5, particularly 70/30 to 90/10, in terms of the mass ratio of the monomer component (X) / monomer component (Y). It is suitable that the acrylic resin (A1) is within the above range from the viewpoint of water dispersion stability of the acrylic resin (A1) and the finish of the clear coating film.

Further, polymerization with a polymerizable unsaturated monomer component other than the above-mentioned polymerizable unsaturated monomer components (X) and (Y) may be appropriately added as necessary.

The reaction temperature for polymerizing the monomers (X) and (Y) is usually in the range of about 60 to about 200 ° C., preferably about 70 to about 160 ° C., and the reaction time is usually about 10 hours or less, preferably about. 0.5 to about 6 hours.

In the above reaction, it is preferable to add a polymerization initiator as appropriate. Examples of such a polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, di-tert-amyl peroxide, and t-butyl. Organic peroxides such as peroxy-2-ethylhexanoate, tert-butylperoxylaurate, tert-butylperoxyisopropyl carbonate, tert-butylperoxyacetate, diisopropylbenzenehydroperoxide; azobisisobutyro Nitrile, azobis (2,4-dimethylvaleronitrile), azobis (2-methylpropionnitrile), azobis (2-methylbutyronitrile), 4,4'-azobis (4-cyanobutanoic acid), dimethylazobis (2) -Methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}, etc. Azo compounds; examples thereof include persulfates such as potassium persulfate, ammonium persulfate, and sodium persulfate.

These polymerization catalysts may be used alone or in combination of two or more. Further, there is no problem even if the type and amount of the polymerization initiator are different at the time of polymerization of the polymerizable unsaturated monomer component (X) and the polymerizable unsaturated monomer component (Y).

The amount of the polymerization initiator to be blended is 0.01 to 20 parts by mass, particularly 0.1 to 15 parts by mass, and more particularly 0.3 to 10 parts by mass, based on 100 parts by mass of the polymerizable unsaturated monomer used at that stage. The range of parts by mass is preferable from the viewpoint of water dispersion stability of the obtained acrylic resin (A1).

The above polymerization is usually carried out in the presence of an organic solvent. The organic solvent can be appropriately selected in consideration of the polymerization temperature, ease of handling during emulsion production, and long-term storage stability of the obtained aqueous dispersion.

It is also possible to add an organic solvent when the acrylic resin is dispersed in water.

As the organic solvent, an alcohol solvent, a cellosolve solvent, a carbitol solvent and the like are preferable. Specifically, for example, alcohol solvents such as n-butanol; ethylene glycol monobutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol mono n-butyl ether, etc. Cellosolve-based solvents such as dipropylene glycol monomethyl ether and dipropylene glycol mono-n-butyl ether; carbitol-based solvents such as diethylene glycol monobutyl ether and diethylene glycol monoethyl ether can be mentioned.

Further, as the organic solvent, an inert organic solvent other than the above that does not mix with water can be used as long as it does not interfere with the water dispersion stability of the acrylic resin (A1), and as this organic solvent, for example, toluene. , Aromatic hydrocarbon solvents such as xylene, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as methyl ethyl ketone and cyclohexanone.

The acrylic resin obtained as described above has a weight average molecular weight in the range of 5,000 to 100,000, particularly 10,000 to 50,000, and more particularly 10,000 to 30,000. It is suitable from the viewpoints of water dispersion stability of the resin (A1) and finishability, smoothness, and polishability of the clear coating film.

In the present specification, for the weight average molecular weight of the acrylic resin, "HLC-8120GPC" (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph device, and one "TSKgel G4000HXL" is used as a column. Two TSKgel G3000HXL "and one" TSKgel G2000HXL "(trade name, all manufactured by Tosoh Corporation) are used, and a differential refractometer is used as a detector. Mobile phase; tetrahydrofuran, It can be measured under the conditions of measurement temperature: 40 ° C. and flow velocity: 1 mL / min.

The acrylic resin (A1) can be a core-shell type acrylic resin emulsion having a copolymer composed of a polymerizable unsaturated monomer component (X) as a core and a polymerizable unsaturated monomer component (Y) as a shell. The average particle size thereof can be in the range of 0.05 to 1.0 μm, preferably 0.08 to 0.8 μm.

In the present specification, the average particle size is defined by diluting the sample with deionized water to a concentration suitable for measurement with a Coulter counter N4 (trade name, manufactured by Beckman Coulter Co., Ltd., particle size distribution measuring device) at room temperature (trade name). The value is measured at about 20 ° C.).

The resin solid content of the acrylic resin (A1) is preferably about 35 to 65% by mass from the viewpoint of dispersion stability of the acrylic resin (A1) in water.

Here, the resin solid content in the present specification is a value calculated by collecting about 2.0 g of a sample in an aluminum foil cup having a diameter of about 5 cm and heating the remaining amount (g) at 110 ° C. for 1 hour. Is.

The hydroxyl value per solid content of the acrylic resin (A1) is 70 to 170 mgKOH / g, particularly 100 to 120 mgKOH, from the viewpoints of finishability, polishability, and finishability after polishing work of the formed clear coating film. The range of / g is preferable.

The acid value of the acrylic resin (A1) per solid content is preferably less than 40 mgKOH / g, particularly preferably in the range of 10 to 35 mgKOH / g, from the viewpoint of dispersion stability of the acrylic resin (A1) in water.

The coating form of the aqueous two-component clear coating composition of the present invention is a two-component composition in which the main agent (I) containing the acrylic resin (A1) and the curing agent (II) containing the polyisocyanate compound described later are mixed immediately before use. Can be a thing.

The content ratio of the acrylic resin (A1) resin solid content contained in the main agent (I) exceeds 70% by mass, particularly 80% by mass or more, based on the total amount of the total resin solid content in the main agent (I). Can be.

<Acrylic resin (A2)>
In the aqueous two-component clear coating composition of the present invention, an acrylic resin (A2) having an acid value in the range of 100 to 300 mgKOH / g per solid content is used in combination with the main agent (1). The acrylic resin (A2) is a water-soluble or water-dispersible acrylic resin, and is usually a mixture of a hydrophilic group-containing polymerizable unsaturated monomer such as a carboxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers. Acrylic resin obtained by copolymerizing the above can be mentioned.

As the polymerizable unsaturated monomer constituting the acrylic resin (A2), those listed in the section of the acrylic resin (A1) can be preferably used, but (meth) acrylic acid is used as a part of the copolymer component. It is preferable to contain methacrylic acid, and particularly preferably to contain methacrylic acid.

Other polymerizable monomers may be contained as long as the coating workability and other coating performance are not impaired. In this case, a (meth) acrylate having an alkyl group having 1 to 2 carbon atoms, particularly methyl. It is preferable to use acrylate and / or ethyl acrylate.

The mass ratio of the (meth) acrylic acid / (meth) acrylate having 1 to 2 carbon atoms among the copolymerization components of the acrylic resin (A2) should be in the range of 15/85 to 70/30 for the finishability. It is particularly suitable in terms of smoothness on a highly coarse object to be coated.

The content of the (meth) acrylic acid is 16 to 80% by mass, particularly 20 to 70% by mass, and more particularly 30 to 50% by mass with respect to the total amount of the copolymerizing components. It is suitable from the viewpoint of ease of use, compatibility with other components, and polishability.

Further, the content of the (meth) acrylate is preferably in the range of 20 to 84% by mass, particularly 30 to 80% by mass, and more particularly 50 to 70% by mass from the viewpoint of polish repairability.

Other polymerizable monomers may be contained as long as the coating workability and other coating film performance are not impaired, but in that case, 0 to 64% by mass, particularly 0 to less than 50% by mass, and particularly 0 to 0. 20% by mass is preferable.

As an example of other polymerizable unsaturated monomers, for example, a polymerizable unsaturated monomer having at least two polymerizable unsaturated groups in one molecule such as allyl (meth) acrylate and 1,6-hexanediol di (meth) acrylate. And so on. These can be used alone or in combination of two or more.

The method for producing the acrylic resin (A2) is not particularly limited, but the acrylic resin (A2) can be produced by the method described in the section of the acrylic resin (A1), a conventionally known emulsion polymerization method, or the like. The emulsion polymerization method is copolymerized in an aqueous dispersion containing, for example, an anionic or nonionic surfactant such as sodium lauryl sulfate and a water-soluble free radical polymerization initiator such as alkali metal persulfate or ammonium persulfate. Can be obtained.

The aqueous two-component clear coating composition of the present invention contains, in particular, a polyisocyanate compound (B) in which acrylic resins (A1) and (A2) are used in combination and the curing agent (II) has an acid group, and a hydroxyl group. By containing the glycol ether-based organic solvent (C) that does not exist, it is excellent in drying property and excellent finish property such as smoothness even when the roughness of the substrate is high, and dripping is unlikely to occur. It has the effect of being excellent in painting workability.

Further, the glass transition temperature of the acrylic resin (A2) is in the range of 0 ° C. to 60 ° C., particularly 15 to 55 ° C., and the clear coating film formed has smoothness and dryness on a highly rough object to be coated. It is particularly preferable from the viewpoint of polishability and polishability.

The content of the acrylic resin (A2) is 100% by mass of the resin solid content of the acrylic resin (A1) from the viewpoint of coating workability and smoothness of the formed clear coating film on a highly coarse object to be coated. It can be 0.01 part by mass or more, within the range of 0.01 to 20 parts by mass, and further within the range of 0.05 to 5 parts by mass.

In addition to the acrylic resin (A), the main agent (I) is a conventionally known paint additive such as a neutralizing agent, a modifying resin, a surface conditioner, and a defoaming agent, depending on the required purpose. Agents, thickeners, ultraviolet absorbers, light stabilizers, organic solvents and the like can be blended.

<Neutralizer>
In order to neutralize the emulsion of the acrylic resin (A) of the present invention, it is particularly preferable that the main agent (I) contains a tertiary amine (D) in the present invention. In particular, by using a tertiary amine as the neutralizing agent, the compatibility with other components is excellent, and the smoothness as a clear coating film is excellent, so that the finish is excellent.

Examples of the tertiary amine (D) include trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tridodecylamine, N, N'-. Tertiary aliphatic alkyl monoamine compounds such as dimethyl dodecylamine and trihexadecylamine, aromatic amines such as dimethylaniline, diethylaniline and trivezylamine, morpholin compounds such as N-methylmorpholin and N-ethylmorpholin, and triethanol. Alkanol amines such as amines, triethylenediamine, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, dibutylethanolamine, di (2-ethylhexyl) ethanolamine, ethyldiethanolamine, triisopropanolamine, dibutylisopropanolamine, tetramethylethylenediamine, tetramethyl Examples thereof include diamine compounds such as hexamethylenediamine, tetramethylpropylenediamine and pentamethyldiethylenetriamine, and triamine compounds.

These can be used alone or in combination of two or more.

In the present invention, the tertiary amine (D) may be blended at any stage of the coating material production, and its content is mixed with the main agent (I) containing the acrylic resins (A1) and (A2) of the present invention. , PH 7 or higher, preferably within the range of 7.5 to 8.5, preferably to the extent that it is adjusted or maintained, and can be adjusted as appropriate.

<Surface conditioner>
The surface conditioner may be contained in the main agent (I) and / or the curing agent (II), but is particularly preferably contained in the main agent (I).

By containing the surface conditioner, the applicability to the base and the leveling property of the coating composition may be adjusted to improve the finish and the physical properties of the coating film, and the foaming suppression and defoaming effects may be expected.

In the present invention, the inclusion of the polyether-modified siloxane (E) as a part of the surface conditioner not only improves the wettability to the substrate, but also improves the compatibility of the coating composition, particularly the acrylic resin ( It is particularly preferable from the viewpoint of compatibility with both A) and the polyisocyanate compound (B) and armpit resistance.

The weight average molecular weight of the polyether-modified siloxane (E) is preferably in the range of 400 to 3,000, particularly preferably in the range of 500 to 2,000.

The weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

As the above (E), a commercially available product can be used, and specific examples thereof include BYK-345, BYK-347, BYK-348, BYK-349, BYK-UV3500, BYK-3510, BYK-3530, BYK-3570. (Product name, manufactured by Big Chemie Japan), TEGO Wet 245, TEGO Wet 250, TEGO Wet 260, TEGO Wet 270, TEGO Wet 280 (Product name, manufactured by Evonik Degussa), etc. be able to.

Examples of the surface conditioner other than the above (E) include silicone-based, acetylene-based, acrylic-based, fluorine-based, vinyl-based, and the like other than (E).

Examples of the silicone-based surface conditioner other than the above (E) include organopolysiloxane such as dimethylpolysiloxane, modified silicone obtained by modifying organopolysiloxane, and the like. Specific examples of the modified silicone include alkyl-modified polysiloxane and phenyl-modified polysiloxane. The structure of the compound may be linear, branched, or a mixture thereof. These can be used alone or in combination of two or more.

Specific examples of the silicone-based surface conditioner other than the above (E) include dimethylpolysiloxane, methylphenylpolysiloxane, polyether-modified polydimethylsiloxane, polyether-modified dimethylpolysiloxane, polyester-modified dimethylpolysiloxane, and polyester. Modified polydimethylsiloxane, polymethylalkylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified polymethylalkylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyether-modified (meth) cryloyl group-containing polydimethylsiloxane, polyester-modified (meth) cryloyl Examples include group-containing polydimethylsiloxane.

As the silicone-based surface conditioner other than the above (E), a commercially available product can be used.

For example, BYK-341, BYK-344, BYK-346, BYK-325, BYK-315, BYK-320, BYK-322, BYK-323, BYK-300, BYK-302, BYK-307, BYK-306, BYK-330, BYK-331, BYK-333, BYK-370, BYK-SILCLEAN3700 (above, product name, manufactured by Big Chemie Japan); DISPALLON 1711, 1751N, 1761, LS-001, LS-050 (above, product) Name, manufactured by Kusumoto Kasei Co., Ltd .; Polyflow KL-100, Polyflow KL-400HF, KL-401, KL-402, KL-403, KL-404, Polyflow KL-700 (above, product name, product manufactured by Kyoeisha Chemical Co., Ltd.) Name), TEGO Twin4000, TEGO Twin4100, TEGO Twin4200 (above, trade name, manufactured by Evonik Degussa), Foamstar ED-2522, Foamstar ST2438 (above, trade name, manufactured by BASF), and the like.

Examples of the acetylene-based surface conditioner include acetylenediol-based and acetylene-modified siloxane-based agents. The acetylene-based surface conditioner is a nonionic surfactant having an acetylene group in the center and having a symmetrical structure, and when added to a coating composition, it may have an effect of preventing foaming.

Specific trade names of acetylene diol-based surface conditioners include Surfinol 104, Surfinol 104E, Surfinol 104H, Surfinol 104A, Surfinol 104BC, Surfinol 104DPM, Surfinol 104PA, Surfinol 104PG-50, and Surfy. Nord 104S, Surfinol 420, Surfinol DF-110D, Surfinol 82, Surfinol 104, Surfinol 504, Surfinol MD-20, Surfinol DF-110D (trade name, manufactured by Air Products), TEGO Wet 520 (trade name, manufactured by Ebony Degusa), TRITON HW-1000 (trade name, manufactured by Dow Chemical Co., Ltd.) and the like can be mentioned.

Specific trade names of the acetylene-modified siloxane-based surface conditioner include Surfinol DF-66 (trade name, manufactured by Air Products & Chemicals, Inc.) and the like.

Specific trade names of fluorine-based surface conditioners include BYK-340, BYK-3455 (above, trade name, manufactured by Big Chemie Japan), Polyflow KL-604, (above, trade name, manufactured by Kyoeisha Chemical Co., Ltd.). ) And so on.

As the acrylic surface conditioner, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and alkyl esters of (meth) acrylic acid can be obtained as raw materials. Acrylic polymers having a weight average molecular weight of 300 to 50,000 can be mentioned. In addition, silicone-modified acrylic resin and the like are also included in this.

As the acrylic surface conditioner, commercially available products can be used, for example, BYK-350, BYK-352, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-392 (above, Product name, manufactured by Big Chemie Japan Co., Ltd .; DISPARLON LF-1980, LF-1982, LF-1983, LF-1984, LF-1985, NSH-8430HF (trade name, manufactured by Kusumoto Kasei Co., Ltd.); Polyflow No. .. 50EHF, No. 54N, No. 55, No. 77, No. 85HF, No. 90, No. 90D-50, No. 95, No. 99C (above, product name, manufactured by Kyoeisha Chemical Co., Ltd.) and the like can be mentioned.

Above all, it is preferable to contain at least one surface conditioner selected from a silicone-based surface conditioner other than (E), an acetylene-based surface conditioner, and an acrylic surface conditioner, and a polyether-modified siloxane (E). Although the mechanism of action is not clear, the polyether-modified siloxane (E), which has a relatively small molecular weight among surface conditioners, contributes to wettability and is also excellent in armpit resistance due to interaction with other components. It may have the effect of being able to obtain a coating film. Among the surface conditioners other than the above (E), it is particularly preferable to use an acetylene-based surface conditioner from the viewpoint of armpit resistance and compatibility with the coating composition.

The solid content of the surface conditioner is generally 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, from the viewpoint of ensuring finishability and wettability to the substrate. Is.

In particular, when the polyether-modified siloxane (E) is contained, the solid content is preferably 0.01 to 5% by mass based on the total resin solid content contained in the main agent. More preferably, it is 0.1 to 3.0% by mass. When the content of the polyether-modified siloxane is within the above range, the wettability of the coating composition may be improved, which is particularly preferable.

When a surface conditioner other than the above (E) is used, the solid content thereof is appropriately in the range of 5 parts by mass or less, preferably 0.1 to 4.0 parts by mass.

The ratio of the polyether-modified siloxane (E) to the other surface conditioner is 1 to 30/99 to 70, particularly preferably 5 to 25 / in terms of solid content mass ratio from the viewpoint of compatibility and armpit resistance. The range of 95 to 75 is preferable.

As the ultraviolet absorber, conventionally known ones can be used, and examples thereof include ultraviolet absorbers such as benzotriazole-based absorbents, triazine-based absorbents, salicylate derivative-based absorbents, and benzophenone-based absorbents.

When the coating composition of the present invention contains an ultraviolet absorber, the blending amount of the ultraviolet absorber is in the range of 0.1 to 10 parts by mass with reference to 100 parts by mass of the solid content in the coating composition. It is more preferable, it is more preferably in the range of 0.2 to 5 parts by mass, and further preferably it is in the range of 0.3 to 3 parts by mass.

As the light stabilizer, conventionally known ones can be used, and examples thereof include hindered amine-based light stabilizers.

When the coating composition of the present invention contains a light stabilizer, the blending amount of the light stabilizer is in the range of 0.1 to 10 parts by mass with reference to 100 parts by mass of the solid content in the coating composition. It is more preferable, it is more preferably in the range of 0.2 to 5 parts by mass, and further preferably it is in the range of 0.3 to 2 parts by mass.

The viscosity of the main agent (I) is preferably in the range of 400 to 2000 mPa · s, preferably 500 to 1,500 mPa · s, from the viewpoint of smoothness of the coating film, particularly sagging.

In the present specification, the viscosity of the main agent (I) was measured at a rotation speed of 60 rpm and a measurement temperature of 25 ° C. using a B-type rotational viscometer: viscometer digital bismetron viscometer VDA type (manufactured by Shibaura System Co., Ltd.). Let it be a value.

The viscosity of the main agent (I) (that is, the structural viscosity index TI) is preferably 1.1 or more, and more preferably in the range of 1.2 to 5.0. The above numerical range of viscosity balances well-balanced that the viscosity of the clear coating composition at the time of spray coating is appropriately lowered to sufficiently wet and spread on the object to be coated, and the flow is suppressed to improve the sagging property. It is suitable from the viewpoint.

The structural viscosity index TI value is defined by the following equation (1).

TI value = Va / Vb ... (1)
(However, in the formula (1), Va is the apparent viscosity (mPa · sec) measured at a rotation speed of 6 times / minute with a rotational viscometer (same as above) at a temperature of 25 ° C., and Vb is the same. Viscosity (mPa · sec) measured at 60 rpm).

≪Curing agent (II) ≫
The present invention requires a polyisocyanate compound (B) having an acid group in the curing agent (II) and a glycol ether-based organic solvent (C) having no hydroxyl group.

The coating form of the aqueous two-component clear coating composition of the present invention is a two-component mixture in which the main agent (I) containing the acrylic resin emulsion (A1) and the curing agent (II) containing the polyisocyanate compound described later are mixed immediately before use. It can be a mold composition.

By combining with the curing agent (II) of the present invention, it has excellent compatibility and can be easily stirred even by hand stirring, and has various performances such as curability and weather resistance, and finishes such as polishability, transparency and smoothness. It has the effect that a film having excellent properties can be formed under relatively mild drying conditions (for example, normal temperature).

The polyisocyanate compound (B) having an acid group is a compound having an acid group and an isocyanate group, and for example, a polyisocyanate is a compound having both a functional group and an acid group reactive with the isocyanate group in the molecule. It can be prepared by reacting.

<Polyisocyanate compound (B)>
Examples of the polyisocyanate for preparing the polyisocyanate compound (B) having an acid group include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and cyclic aliphatic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate. Classes; aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate; triphenylmethane-4,4', 4'-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4 , 6-Triisocyanatotoluene, 4,4'-dimethyldiphenylmethane-2,2', 5,5'-tetraisocyanate and other organic polyisocyanates themselves, such as polyisocyanate compounds with three or more isocyanate groups, or Examples thereof include additions of each of these organic polyisocyanates to a polyhydric alcohol, a low molecular weight polyester resin, water, etc., a cyclized polymer of each of the above-mentioned organic polyisocyanates, and an isocyanate / biurette. Of these, aliphatic diisocyanates are preferable from the viewpoint of adjusting the polyisocyanate compound (B).

Examples of the acid group contained in the compound for reacting with the polyisocyanate include a carboxyl group, a phosphoric acid group, and a sulfonic acid group.

The polyisocyanate compound (B) having an acid group may have a polyether chain in addition to the acid group.

Further, in the present invention, the curing agent (II) may contain a polyisocyanate compound other than the above (B) in addition to the polyisocyanate compound (B) having an acid group.

As the polyisocyanate compound other than the above (B), those conventionally used for organic solvent type paints can be used without limitation, and examples thereof include polyisocyanates having no acid group or nonionic group. Specifically, aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; cyclic aliphatic diisocyanates such as hydrogenated xylylene diisocyanate and isophorone diisocyanate; aromatics such as tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate. Diisocyanates; triphenylmethane-4,4', 4'-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4'-dimethyldiphenylmethane-2 Organic polyisocyanates such as polyisocyanate compounds having three or more isocyanate groups such as, 2', 5,5'-tetraisocyanate, or each of these organic polyisocyanates and polyhydric alcohol, low molecular weight polyester resin or water. The above-mentioned cyclized polymers of each of the organic polyisocyanates, the isocyanate / biuret form, and the like can be mentioned, and they can be used alone or in combination of two or more. Of these, cyclized polymers, especially cyclized polymers of aliphatic diisocyanates, are suitable.

Further, a nonionic polyether-modified polyisocyanate obtained by modifying the polyisocyanate compound listed in the above description (B) with a polyether compound can also be exemplified.

When a polyisocyanate compound other than the above (B) is used in combination, the ratio of the polyisocyanate compound (B) having an acid group is such that the above (B) is 10% by mass or more in the total mass of all the polyisocyanate compounds. It is preferably in the range of 40 to 100% by mass from the viewpoint of water resistance of the clear coating film and compatibility with the acrylic resin (A).

In the present invention, the curing agent (II) requires the polyisocyanate compound (B) and may contain a polyisocyanate component other than the above (B), and is used for organic solvents, dehydrating agents, and paints. Additives and the like can be appropriately added.

<Organic solvent>
The aqueous two-component clear coating composition of the present invention is an aqueous coating material, but by containing a glycol ether-based organic solvent (C) having no hydroxyl group in the curing agent (II), the acrylic resin (A) It is particularly preferable because the miscibility between the and the polyisocyanate compound (B) can be improved.

In addition, in this specification, a water-based paint is a term contrasted with an organic solvent type paint, and generally, a coating film-forming resin is dissolved or dissolved in water or a medium containing water as a main component (water-based medium). It means a dispersed paint. The content of water in the aqueous two-component clear coating composition of the present invention is preferably in the range of 10 to 90% by mass, preferably 20 to 80% by mass, and more preferably 30 to 70% by mass. Is.

The glycol ether having no hydroxyl group is a compound in which both the hydroxyl groups of the glycol described later are etherified.

The glycol constituting the glycol ether is, for example _{, a diol represented by the general formula C n} H _2n (OH) ₂ (n represents an integer of 2 to 20) or a condensate of one or more of the above diols. Also good, specifically ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, isoprene glycol, 1,2-pentylene glycol, 1 , 2-Hexylene glycol, octylene glycol and the like, examples of the condensate include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Ethylene glycol, propylene glycol and 1,3-butylene glycol are preferable.

Specific examples of the glycol ether-based organic solvent (C) having no hydroxyl group include ethylene glycol diether, diethylene glycol diether, triethylene glycol diether, tetraethylene glycol diether, propylene glycol diether, and dipropylene glycol. Examples thereof include diether, tripropylene glycol diether, butylene glycol diether, and the like. Specifically, ethylene glycol diether such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol divinyl ether, and diethylene glycol. Diethylene glycol diether such as ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether; triethylene glycol diether such as triethylene glycol dimethyl ether and triethylene glycol divinyl ether; tetraethylene glycol diether such as tetraethylene glycol diethyl ether, etc. Propylene glycol di, such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol diisopropyl ether, propylene glycol di-n-butyl ether, propylene glycol diisobutyl ether, propylene glycol diallyl ether, and propylene glycol diphenyl ether. Ethers; dipropylene glycol diethyl ether, and dipropylene glycol diethers such as dipropylene glycol di-n-butyl ether, dipropylene glycol diisobutyl ether, and dipropylene glycol allyl ether; tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tri. Tripropylene glycol diether such as propylene glycol di-n-butyl ether, tripropylene glycol diisobutyl ether, tripropylene glycol diallyl ether; butylene glycol di such as butylene glycol dimethyl ether, butylene glycol diethyl ether, and butylene glycol di-n-butyl ether. Ether, etc., 2-butoxyethyl diethoxyethyl ether, 2-butoxyethylto Examples thereof include riethoxy ether and 2-butoxyethyl tetraethoxyethyl ether.

Among them, at least one selected from ethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and diethylene glycol isopropyl methyl ether is particularly preferable as the above (C).

In addition to the above (C), other organic solvents may be contained.

As the organic solvent other than the above (C), it is preferable to appropriately select a solvent having no hydroxyl group because it may react with the above-mentioned polyisocyanate compound (B). Examples include systems and ether systems.

Examples of acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether acetate (also known as n-butyl celloacetate acetate), diethylene glycol monoethyl ether acetate, and diethylene glycol mono-n-butyl ether acetate, 3 -Examples include alkylene glycol ether acetate having no hydroxyl group such as methoxybutyl acetate and propylene glycol monomethyl ether acetate.

Examples of the ketone system include acetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone and the like.

Examples of the ester system include ethyl acetate (also known as ethyl acetate), butyl acetate (also known as butyl acetate), isobutyl acetate (also known as isobutyl acetate), methyl benzoate (also known as methyl benzoate), ethyl ethoxypropionate, and propion. Examples thereof include ethyl acetate and methyl propionate.

Examples of the ether type include tetrahydrofuran, dioxane, dimethoxyethane, aromatic hydrocarbons, aliphatic hydrocarbons and the like.

The organic solvents can be appropriately combined and used according to the purpose of adjusting the viscosity, adjusting the coatability, and the like.

Among the organic solvents, the content of (C) may be adjusted to 20% by mass or more, particularly preferably 40 to 100% by mass, based on the total amount of the total organic solvent of the curing agent (II). It is particularly preferable from the viewpoint of miscibility with the polyisocyanate compound (B), that is, finishability.

Of the organic solvents, when an organic solvent other than the above (C) is used in combination, it is preferable to use an acetate type and / or an ester type, and the content ratio in that case is 5 with respect to the total amount of the total organic solvent. It is preferable to adjust the amount in the range of ~ 50% by mass, more preferably 10 to 30% by mass.

≪Aqueous two-component clear paint composition≫
The aqueous two-component clear coating composition of the present invention can be coated by mixing the main agent (I) containing the acrylic resin (A) and the curing agent (II) immediately before use and appropriately diluting them.

The object to be coated of the aqueous two-component clear coating composition of the present invention is not particularly limited, and is, for example, a metal such as iron or aluminum; an inorganic material such as a slate plate or a PC plate; an organic material such as plastic; paper, Examples include cardboard and wood. These coated surfaces may be coated with a water-based or solvent-based paint, or may be a damaged painted body.

≪Coating film forming method≫
The coating film forming method of the present invention is not particularly limited, but
For example, it can be suitably used in the following repair painting method.

For damaged parts of the painted body
(1) A process of filling or painting a base treatment agent to form a base treatment layer.
(2) A process of drying and polishing the formed base treatment layer,
(3) A step of applying a colored base coat coating composition for repair on a polished base treatment layer to form a colored base coating film.
(4) A step of coating the aqueous two-component clear coating composition of the present invention on the colored base coating film obtained in the step and drying it can be included.

(1) A step of forming a base treatment layer.

As the base treatment material, it can be used without particular limitation, and examples thereof, which are conventionally known, include a putty composition and a primer surfacer. By coating the base treatment material, it is possible to protect the exposed portion of the damaged portion of the coated body or the uneven bare ground, and to improve the adhesion to the colored base coating film described later.

As a method of filling or painting the base treatment agent, for example, a spatula or the like can be used. Before painting or filling the base treatment agent, cleaning, sanding with sandpaper, or the like may be performed in advance around the damaged portion of the coated body.

(2) A step of drying and polishing the base treatment layer.

Examples of the drying method include normal temperature drying and forced drying, and the inside of the coating film can be cured by this drying step. In the case of normal temperature drying, specifically, it can be allowed to stand at room temperature for 5 hours or more, or in the case of forced drying, it can be heated at 40 to 120 ° C. for 5 to 60 minutes. In the case of the forced drying, from the viewpoint of finishability, it can be set (standing) at room temperature for 2 to 30 minutes in advance before heat curing. For drying, for example, a blower or the like may be used.

As a method of polishing, for example, water resistant paper or sandpaper can be used.

(3) A step of forming a colored base coating film.

For example, a repair coating composition can be used to form a colored base coating.

The repair paint composition includes acrylic lacquer, acrylic-melamine resin paint, two-component urethane curable paint containing hydroxyl group-containing resin and polyisocyanate compound, acid-epoxy curable paint, fluororesin paint, and alkyd resin. It can be used without particular limitation, such as commonly used organic solvent-based paints such as alkyd-melamine resin-based paints and polyester-melamine resin-based paints, water-based paints, undercoat paints such as powders, coloring base paints, and top clear paints.

In particular, it is preferable to use a colored base coating composition for repair from the viewpoint of base hiding property.

In particular, from the viewpoint of odor and other effects on the human body and the environment, the coloring base coating composition contains a water-soluble resin and / or a water-dispersible resin, a coloring pigment and / or a bright pigment as a main component. Is preferable.

The colored base paint may be applied and then dried, and examples thereof include room temperature drying and forced drying. In the case of normal temperature drying, specifically, it can be allowed to stand at room temperature (for example, less than 10 to 40 ° C.) for 5 hours or more, or in the case of forced drying, it can be heated at 40 to 120 ° C. for 5 to 60 minutes. .. In the case of the forced drying, from the viewpoint of finishability, it can be set (standing) at room temperature for 2 to 30 minutes in advance before heat curing. For drying, for example, a blower or the like may be used.

(4) A step of painting and drying an aqueous two-component clear paint composition.

Examples of the method for applying the aqueous two-component clear coating composition of the present invention include air spray, airless spray, rotary atomization, brush, roller, hand gun, universal gun, immersion, roll coater, curtain flow coater, and roller curtain. Examples thereof include a coater and a die coater, which can be appropriately selected depending on the intended use of the object to be coated, and may be coated a plurality of times.

The coating material of the present invention can form a clear coating film having excellent finish and polishability by forced drying, but the drying conditions in the step (4) are not particularly limited and are baked and dried. Alternatively, it may be dried at room temperature.

In the case of forced drying, it can be heated at 40 to 120 ° C. for 10 to 120 minutes.

The dry film thickness can be in the range of 5 to 500 μm, more 10 to 100 μm, and more particularly 15 to 80 μm from the viewpoint of ensuring a film thickness that can be polished and repaired and the finishability.

When the paint of the present invention is used for repair painting of an automobile or the like, a polishing step (5) may be performed after the step (4).

Examples of the polishing method include a method in which the repair clear coating film is water-polished using water-resistant abrasive paper, and then the polished surface is sequentially polished with a compound for rough polishing and a compound for finish polishing, whereby the glossiness is increased. It is possible to obtain a repair clear coating film that is excellent in gloss and gloss and has an inconspicuous difference in appearance from the unrepaired part.

Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified, "parts" and "%" indicate "parts by mass" and "% by mass".

≪Acrylic resin emulsion manufacturing method≫
(Production Example 1) Acrylic resin No. Production of A1-1 Emulsion 50 parts of propylene glycol monopropyl ether is placed in a glass four-necked flask equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet, and the temperature rises to 120 ° C under a nitrogen stream while stirring. did. When the temperature reached 120 ° C., a mixed solution 1 in which 1.5 parts of t-butylperoxy-2-ethylhexanoate was premixed with the monomer formulation and the polymerization initiator shown in the first step column of Table 1 was mixed for 4 hours. After the dropping was completed, the mixture was kept at a temperature of 120 ° C. for 1 hour.
While maintaining the temperature of 120 ° C., 0.3 part of t-butylperoxy-2-ethylhexanoate and 0.3 part of the monomer formulation described in the column of the second step of Table 1 were premixed in the flask. The mixed solution 2 was added dropwise over 1 hour, and after the addition was completed, the mixture was kept at 120 ° C. for 1.5 hours to obtain an acrylic polyol solution.
The resin solid content of the obtained acrylic polyol solution was 77.5%, and the weight average molecular weight was 14,000. Subsequently, propylene glycol monopropyl ether was distilled off from the obtained acrylic polyol solution under reduced pressure until the solid content became 85%. This was cooled to 95 ° C., the pH was adjusted to 8.0 with dimethylethanolamine, and the mixture was stirred for 30 minutes. Further, while stirring, deionized water was added dropwise over 2 hours so that the resin solid content became 45%, and the acrylic resin No. An emulsion of A1-1 was obtained. Table 1 shows the weight average molecular weight of the obtained acrylic resin A1-1, the acid value per resin solid content, the hydroxyl value, the glass transition temperature, and the average particle size of the emulsion.

(Manufacturing Examples 2 to 4)
In Production Example 1, the acrylic resin No. 1 was the same as in Production Example 1 except that the monomer composition and the blending amount of each copolymerization component were as shown in Table 1 below. A1-2, A1-3 and A1'-1 emulsions were obtained. Acrylic resin No. Table 1 shows the weight average molecular weights of A1-2, A1-3, and A1'-1, the acid value per resin solid content, the hydroxyl value glass transition temperature, and the average particle size of the emulsion.

(Production Example 5) Acrylic resin No. Production of A2-1 emulsion 28.5 parts of deionized water, "Newcol 707SF" (manufactured by Nippon Emulsifier Co., Ltd., trade name, anionic emulsifier, solid) in a reaction vessel equipped with a reflux condenser, agitator, a thermometer, and a dropping funnel. 30%) 0.12 part was added, and the temperature was maintained at 80 ° C. after nitrogen substitution. 0.1 part of ammonium persulfate was added thereto, and 20 minutes after the addition, a pre-emulsion obtained by emulsifying the following composition was added dropwise over 4 hours.
Deionized water 36.1 parts Ethyl acrylate 57.5 parts Methacrylic acid 42.0 parts 1,6-hexanediol diacrylate 0.5 parts 30% Newcol 707SF 6.6 parts Ammonium persulfate 0.2 parts After dropping It was kept at 80 ° C. for another 2.5 hours. After that, the temperature was lowered to 40 ° C. or lower while adding deionized water, the pH was adjusted to 7 to 8 with aqueous ammonia, and the acrylic resin emulsion No. with a solid content concentration of 50%. A2-1 was obtained. Table 2 also shows the acid value, hydroxyl value, and glass transition temperature of the obtained acrylic resin per resin solid content.

(Production Example 6 and Production Example 7)
In Production Example 5, an emulsion of acrylic resins A2-2 and A2'-1 (for comparison) having a solid content concentration of 50% was obtained in the same manner as in Production Example 5 except that the monomer composition of the copolymerization component was shown in Table 2. It was.

<How to adjust the water-based two-component clear paint composition>
(Example 1) Aqueous two-component clear coating composition No. 1
Acrylic resin No. obtained in Production Example 1. 220 parts (99 parts solid content) of 45% solution of A1-1 emulsion, acrylic resin No. obtained in Production Example 6. 2 parts of 50% solution of A2-1 emulsion (1 part of solid content), 0.5 part of BYK-348 (Note 1), 4.0 parts of Surfinol 104A (Note 3) 4.0 parts (2.0 parts of solid content), TINUVIN384 -2 (Note 6) 2.1 parts (solid content 2.0 parts by mass) and TINUVIN 292 (Note 7) 1.0 part were stirred to prepare the main agent (I). In a separate container, as a curing agent (II), 65 parts of Bihzur XP 2655 (Note 9), 39 parts of dimethylpropylene glycol (Note 12), 13 parts of ethylene glycol monobutyl ether acetate (Note 16), diethylene glycol monoethyl ether acetate (Note 17). ) 13 parts are uniformly mixed to prepare, and the curing agent (II) and the diluting water are added to the main agent (I) so that the solid content content is 40% by mass, and the mixture is stirred to form an aqueous two-component clear. Paint composition No. I got 1. Table 3 shows the viscosity characteristics of each main agent before the curing agent (II) was added.

(Examples 2 to 13, Comparative Examples 1 to 5) Aqueous two-component clear coating composition No. 2-19
In Example 1, the composition of an aqueous two-component clear coating material having a solid content of 40% by mass shown in Tables 3 to 5 is the same as in Example 1 except that the composition of each component is the composition shown in Tables 3 to 5. Item No. 2 to 19 were obtained. The blending amounts in Tables 3 to 5 indicate the blending amounts of the solid content.

Note 1) BYK-348: Product name, manufactured by Big Chemie Japan, polyether-modified siloxane, weight average molecular weight 1,500, solid content 100% by mass,
Note 2) BYK-345: Trade name, manufactured by Big Chemie Japan, polyether-modified siloxane, weight average molecular weight 1,300, solid content 100% by mass.

Note 3) Surfinol 104A: Trade name, Air Products & Chemicals, acetylenediol-based surface conditioner (/ defoamer), solid content 50% by mass, 2-ethylhexanol solution,
Note 4) BYK-301: Product name, manufactured by Big Chemie Japan, silicone-based surface conditioner, solid content 100% by mass,
Note 5) BYK-025: Product name, manufactured by Big Chemie Japan, silicone-based surface conditioner, polyether-modified dimethylpolysiloxane, solid content 100% by mass,
Note 6) TINUVIN 384-2: Trade name, manufactured by BASF, benzotriazole-based ultraviolet absorber, solid content 95% by mass, 1-methoxy-2-propyl acetate 5% by mass.

Note 7) TINUVIN 292: Trade name, manufactured by BASF, hindered amine-based light stabilizer, solid content 100% by mass.

Note 8) Dropping an amount having a pH of 7.6: All the components of the main agent (I) were mixed, and the neutralizing agent was added dropwise at room temperature (for example, 23 ° C.) until the pH reached 7.6.

Note 9) Bihyzur XP2655: Trade name, manufactured by Sumika Cobestrourethane, hexamethylene diisocyanate polyisocyanate having a sulfonic acid group, NCO content 21%, solid content 100% by mass,
Note 10) Bihyzur XP2487 / 1: Trade name, manufactured by Sumika Cobestrourethane, hexamethylene diisocyanate polyisocyanate having a sulfonic acid group, NCO content 20.6%, solid content 100% by mass,
Note 11) Bihijour 3100: Trade name, manufactured by Sumika Covestro Urethane Co., Ltd., polyethylene glycol-modified hexamethylene diisocyanate-based polyisocyanate, NCO content 17.3%, solid content 100% by mass.

Note 12) Didimethylpropylene diglycol: CASNo. 111109-77-4, glycol ether-based organic solvent without hydroxyl group, molecular weight 162 g / mol, boiling point 171 ° C, solubility in water 32.6 wt% (20 ° C), HLB value (Davis method) 7.1,
Note 13) Diethylene glycol isopropyl methyl ether: CAS No. 77078-22-9, glycol ether-based organic solvent without hydroxyl group, molecular weight 162 g / mol, boiling point 179 ° C, solubility in water ∞, HLB value (Davis method) 7.1,
Note 14) Propylene glycol dimethyl ether: CAS No. 7778-85-0, glycol ether-based organic solvent having no hydroxyl group, molecular weight 104 g / mol, boiling point 97 ° C., solubility in water 43.6, HLB value (Davis method) 7.2,
Note 15) Diethylene glycol diethyl ether: CASNo. 112-36-7, glycol ether-based organic solvent without hydroxyl group, molecular weight 162 g / mol, boiling point 189 ° C, solubility in water ∞, HLB value (Davis method) 7.1,
Note 16) Ethylene glycol monobutyl ether acetate: CASNo. 112-07-2, acetate-based organic solvent, molecular weight 160.2 g / mol, boiling point 195.5 ° C., solubility in water 1.1, HLB value (Davis method) 7.7,
Note 17) Diethylene glycol monoethyl ether acetate: CASNo. 112-15-2, acetate-based organic solvent, molecular weight 176 g / mol, boiling point 217.4, solubility in water 0.7, HLB value (Davis method) 7.3,
Note 18) Butyl acetate: CAS No. 123-86-4, molecular weight 116 g / mol, boiling point 126 ° C., solubility in water 0.7, HLB value (Davis method) 7.3.

<How to make a painted plate>
A coating film was formed on each of the compositions obtained in the above examples by the following object to be coated and the method to prepare a test plate.

Object to be coated 1. Polypropylene plate (abbreviation: PP)
A polypropylene (PP) plate cut into 150 mm × 450 mm × thickness 0.8 mm was used as the object to be coated 1.

Object to be coated 2. Water-based colored base coating film A coated plate coated with a clear paint for an automobile body was polished and degreased with # 800 water-resistant paper to obtain an object to be coated. When this object to be coated is placed horizontally, the water-based coloring base paint composition Retan WB Eco Base (trade name, water-based metallic base paint for automobile repair manufactured by Kansai Paint Co., Ltd.) becomes uniform under the conditions of 25 ° C. and 40% relative humidity. It was spray-painted once. Then, air blowing was performed until the glossiness of the base coating film became 25 or less to prepare a dry coating film. Further, the same water-based coloring base coating composition was overcoated on the dry coating film by spray coating, and air blown until the glossiness became 25 or less (second coating). Further, the same water-based coloring base coating composition was overcoated on the dry coating film by spray coating, and air blown until the glossiness became 25 or less (third coating). After completion of coating, a base coat coating film having a dry film thickness of 15 μm was obtained. The plate on which this water-based coloring base coating film was formed was designated as the object to be coated 2.

Object to be coated 3. Solvent-colored base coating film The same applies to the object 2 except that the aqueous-colored base coating composition is the solvent-coloring base coating composition Retan PG Hybrid Eco-base (trade name, solvent coating for automobile repair manufactured by Kansai Paint Co., Ltd.). 3 was obtained as an object to be coated 3 on which a solvent-colored base coating film was formed.

Manufacturing method (1)
Each of the aqueous two-component clear coating compositions obtained above was spray-coated on the object to be coated 1 so that the dry film thickness was 50 μm. Next, it was dried at 80 ° C. for 30 minutes using an electric hot air dryer and left for 1 day to prepare a test coating plate.

Manufacturing method (2)
Each of the aqueous two-component clear coating compositions obtained above is air-spray coated on the object to be coated 2 or 3 to be coated with an air spray so that the dry film thickness is 40 μm, and then the coated plate is horizontally coated at room temperature for 20 minutes. Then, it was dried at 60 ° C. for 30 minutes using an electric hot air dryer and cooled to room temperature to prepare a test coating plate obtained.

≪Test method≫
Note 19) Painting workability:
Each of the aqueous two-component clear coating compositions was air-spray coated on the object to be coated 2 on which the aqueous coloring base coating film described in the method for producing the test plate (2) was formed. The coating workability was evaluated by observing the wettability and sagging property of the substrate.

<Solidity of substrate> Object to be coated 2
The wettability was evaluated by visually evaluating the appearance of the coating film surface immediately after spray-coating each aqueous two-component clear coating composition on the plate 2 to be coated.
◎: Good,
◯: There is a slight unevenness on the coated surface on the wet coating film, but there is no problem.
Δ: There is a problem with unevenness on the coated surface on the wet coating film.
X: The coated surface on the wet coating film has irregularities, pinholes, etc., which is clearly a problem.

<Sauce> Object to be coated 2
Similarly, the water-based two-component clear coating composition is sprayed onto the plate 2 to be coated by varying the dry film thickness, and the coating film immediately after coating is coated with the coated plate together with the coated plate at a relative humidity of 60 ° to the horizontal. It was allowed to stand at room temperature in an environment of 20 ° C. and 60% relative humidity while holding 50% and 2, and the limit film thickness at which sagging occurred was visually evaluated.
⊚: 50 μm or more,
◯: 30 μm or more and less than 50 μm,
Δ: 10 μm or more and less than 30 μm,
X: Less than 10 μm.

Note 20) Finishability:
The finishability of each aqueous two-component clear coating composition was evaluated.
Regarding the glossiness, gloss, and coated skin, each coated plate prepared by the test plate manufacturing method (1) and the test board manufacturing method (2) was evaluated.
As for the armpit, each coated plate produced by the test plate manufacturing method (1) was evaluated as a test board.
Regarding the appearance, among the test coating plates prepared by the test plate manufacturing method (2), each test plate prepared with the object to be coated 2 was evaluated.

<Glossiness>
The glossiness of each coated surface was measured according to the mirror glossiness (60 degrees) of JIS K5600-4-7 (1999). The measured glossiness was evaluated according to the following criteria.
⊚: Mirror gloss is 100 or more,
◯: Mirror gloss is 85 or more and less than 100,
Δ: Mirror gloss is 70 or more and less than 85,
X: Mirror gloss is less than 70.

<Gloss (visual)>
Similarly, the following was visually evaluated.
◎: Very good smoothness and gloss,
◯: Smoothness, glossiness and no problem level,
△: There is a problem with some glossiness.
X: There is a clear problem with marked glossiness.

<Painted skin (visual)>
Similarly, the following was visually evaluated.
◎: Very good with no dusty skin or yuzu skin on the paint film.
◯: There is almost no problem with dusty skin or citron skin on the paint film.
Δ: There is a problem with dusty skin or citron skin of the coating film.
X: Dust skin or citron skin of the coating film is remarkably observed, and there is a clear problem.

<Waki (visual)> Only the object to be coated 1 The armpit property of the following visual evaluation was evaluated for each test plate (object to be coated 1.) obtained by the test plate preparation method (1).
◯: There are underarm marks on the painted surface,
X: No armpit marks are generated on the coated surface.

<Appearance (transparency and repairability)> Only for the object to be coated 2 The state of the coating film on each test plate was visually observed to check the appearance of the coating film such as turbidity.
⊚: There is no turbidity or cloudiness, and there is almost no difference between the repaired part and the surrounding part, which is good.
◯: There is no turbidity or cloudiness, but there is a slight difference between the repaired part and the surrounding part, but there is no problem in practical use.
Δ: Some turbidity, cloudiness, etc. are observed, and there is a difference between the repaired part and the surrounding part.
X: Remarkably turbidity and cloudiness are observed, and there is a clear problem as a clear coating film.

Note 21) Dryness (polishable time):
Each coating composition is applied as a top clear finish on the base coating film of the object to be coated 2 on which the water-based coloring base coating film according to the method (2) for producing the test plate is formed. The composition was air-spray coated so that the dry film thickness was 40 μm, and then the coated plate was kept horizontally at room temperature for 20 minutes, then dried at 60 ° C. for a predetermined time using an electric hot air dryer and cooled to room temperature. A process test coating plate (for evaluation of dryness) obtained in the above process was prepared. When each test plate was repaired by the following polishing repair method, the drying property was evaluated according to the drying time during which it was possible to polish very well without leaving paper scratches or reducing the glossiness.

(Polished repair method)
After water polishing each test coating plate (for evaluation of dryness) with # 2000 water-resistant abrasive paper, polish the rough-polishing buff with a rough-polishing compound for 60 seconds to remove paper scratches caused by the water-resistant abrasive paper. Further, the finishing buff was polished with a finishing compound for 60 seconds to remove buffing scratches.
When the polishable time is 45 minutes or less, the drying property is excellent, and the longer the polishing time, the worse the drying property.

Claims (8)

In the aqueous two-component clear coating composition containing the main agent (I) containing an acrylic resin and the curing agent (II), the acid value of the main agent (I) is 10 or more and less than 40 mgKOH / g, and the glass transition temperature is 40 ° C. to 53. With ~ 85 ° C acrylic resin (A1) , which is within the range of ° C,
Acrylic resin (A2) with an acid value in the range of 196 to 300 mgKOH / g.
The content of the acrylic resin (A2) is within the range of 0.01 to 6.38 parts by mass of the resin solid content with respect to 100 parts by mass of the resin solid content of the acrylic resin (A1). ,
A polyisocyanate compound (B) having at least one acid group of a carboxyl group, a phosphoric acid group, and a sulfonic acid group in the curing agent (II), and
A water-based two-component clear coating composition for repair coating, which comprises a glycol ether-based organic solvent (C) having no hydroxyl group. The aqueous two-component clear coating composition for repair coating according to claim 1, further comprising a tertiary amine (D) in the main agent (I). The acrylic resin (A1) is a water-dispersible hydroxyl group-containing acrylic resin having a core-shell type structure, and the polymerizable unsaturated monomer component (X) constituting the core portion is an epoxy group-containing non-polymerizable resin. The polymerizable unsaturated monomer component (Y) containing the saturated monomer (a1), the hydroxyl group-containing polymerizable unsaturated monomer (a2) and the other polymerizable unsaturated monomer (a3) and constituting the shell portion is carboxyl group-containing polymerizable. The aqueous two-component clear coating composition for repair coating according to claim 1 or 2, which comprises an unsaturated monomer (b1), a hydroxyl group-containing polymerizable unsaturated monomer (b2), and another polymerizable unsaturated monomer (b3). Stuff. The acrylic resin (A2) contains (meth) acrylic acid and a (meth) acrylate having an alkyl group having 1 to 2 carbon atoms as at least a part of the copolymerization component, and the alkyl having 1 to 2 carbon atoms. The (meth) acrylate having a group is at least one polymerizable unsaturated monomer selected from methyl (meth) acrylate and ethyl (meth) acrylate, and (meth) acrylic acid / (meth) having 1 to 2 carbon atoms. ) The water-based two-component clear coating composition for repair coating according to any one of claims 1 to 3, wherein the mass ratio of acrylate is in the range of 10/90 to 70/30. Further, the aqueous two-component clear for repair coating according to any one of claims 1 to 4 , which contains a polyether-modified siloxane (E) as a surface conditioner in the main agent (I) and / or the curing agent (II). Paint composition. The method according to any one of claims 1 to 5 , wherein the structural viscosity index R of the main agent (I) of the aqueous two-component clear coating composition measured under the following conditions is in the range of 1.1 to 5.0. Aqueous two-component clear paint composition for repair painting.
The structural viscosity index TI value is defined by the following equation (1).
TI value = Va / Vb ... (1)
(However, in equation (1), Va is rotated 6 times by a rotational viscometer (B-type rotational viscometer: viscometer digital bismetron viscometer VDA type (manufactured by Shibaura System Co., Ltd.)) at a temperature of 25 ° C. It is the apparent viscosity (mPa · sec) measured in minutes, and Vb is the viscosity (mPa · sec) also measured at 60 rotations / minute). For damaged parts of the painted body
Step of filling or painting a base treatment agent to form a base treatment layer (1),
Step of drying and polishing the formed base treatment layer (2),
Step (3) of coating a colored base coat coating composition for repair on a polished base treatment layer to form a colored base coating film.
The step (4) of coating the colored base coating film obtained in the step (3) with the aqueous two-component clear coating composition according to any one of claims 1 to 6 and drying it.
A repair painting method for a painted body, which comprises. The coated body according to claim 7 , wherein the colored base coat coating composition for repair is a water-based base coat coating composition containing a water-soluble resin and / or a water-dispersible resin, a coloring pigment and / or a bright pigment as a main component. Repair painting method.